1. which substance is a nonelectrolyte?\na. nacl\nb. (nh4)2so4\nc. h2o2\nd. koh\n\n2. which pair of…

1. which substance is a nonelectrolyte?\na. nacl\nb. (nh4)2so4\nc. h2o2\nd. koh\n\n2. which pair of compounds will form a solution?\na. benzene (c6h6) and hexane (c6h14)\nb. na2so4 and benzene (c6h6)\nc. nacl and hexane (c6h14)\nd. h2o and ccl4\ne. more than one of the combinations above will form solutions.\n\n3. a solution is made by mixing 569 ml of water and 238 ml ethanol. what is the concentration of ethanol in units of volume/volume percent?\na. 41.8% (v/v) ethanol\nb. 0.418% (v/v) ethanol\nc. 29.5% (v/v) ethanol\nd. 0.295% (v/v) ethanol\ne. 70.5% (v/v) ethanol\n\n4. what is the molarity of a solution made by dissolving 3.09 moles of nacl in 1.50 l of solution?\na. 4.64 m nacl\nb. 4.85 m nacl\nc. 2.06 m nacl\nd. 0.673 m nacl\n\n5. how many milliliters of a 5.25% (w/v) hcl solution must be used to prepare 250 ml of a 0.175% (w/v) hcl solution?\na. 8.3 ml hcl solution\nb. 7,500 ml hcl solution\nc. 230 ml hcl solution\nd. 240 ml hcl solution\ne. 8.6 ml hcl solution

1. which substance is a nonelectrolyte?\na. nacl\nb. (nh4)2so4\nc. h2o2\nd. koh\n\n2. which pair of compounds will form a solution?\na. benzene (c6h6) and hexane (c6h14)\nb. na2so4 and benzene (c6h6)\nc. nacl and hexane (c6h14)\nd. h2o and ccl4\ne. more than one of the combinations above will form solutions.\n\n3. a solution is made by mixing 569 ml of water and 238 ml ethanol. what is the concentration of ethanol in units of volume/volume percent?\na. 41.8% (v/v) ethanol\nb. 0.418% (v/v) ethanol\nc. 29.5% (v/v) ethanol\nd. 0.295% (v/v) ethanol\ne. 70.5% (v/v) ethanol\n\n4. what is the molarity of a solution made by dissolving 3.09 moles of nacl in 1.50 l of solution?\na. 4.64 m nacl\nb. 4.85 m nacl\nc. 2.06 m nacl\nd. 0.673 m nacl\n\n5. how many milliliters of a 5.25% (w/v) hcl solution must be used to prepare 250 ml of a 0.175% (w/v) hcl solution?\na. 8.3 ml hcl solution\nb. 7,500 ml hcl solution\nc. 230 ml hcl solution\nd. 240 ml hcl solution\ne. 8.6 ml hcl solution

Answer

Explanation:

Step1: Recall non - electrolyte definition

Non - electrolytes do not dissociate into ions in solution. NaCl, $(NH_4)_2SO_4$, and KOH are ionic compounds that dissociate. $H_2O_2$ is a covalent compound and does not dissociate into ions in solution.

Step2: Analyze solution - forming pairs

Like dissolves like. Benzene and hexane are both non - polar hydrocarbons and will form a solution. Ionic compounds ($Na_2SO_4$, NaCl) are polar and do not dissolve in non - polar hexane or benzene. Water and $CCl_4$ are polar and non - polar respectively and do not form a solution.

Step3: Calculate volume/volume percent

The formula for volume/volume percent ($v/v$) is $\text{%}(v/v)=\frac{V_{solute}}{V_{solution}}\times100%$. The volume of solute (ethanol) is $V_{ethanol}=238\ mL$ and the volume of solution is $V_{solution}=238 + 569=807\ mL$. So $\text{%}(v/v)=\frac{238}{807}\times100%\approx29.5%$.

Step4: Calculate molarity

The formula for molarity ($M$) is $M=\frac{n}{V}$, where $n$ is the number of moles of solute and $V$ is the volume of solution in liters. Given $n = 3.09$ moles and $V=1.50\ L$, then $M=\frac{3.09}{1.50}=2.06\ M$.

Step5: Use dilution formula

The dilution formula is $C_1V_1 = C_2V_2$. Let $C_1 = 5.25%$, $V_1$ be the volume we want to find, $C_2=0.175%$, and $V_2 = 250\ mL$. Then $V_1=\frac{C_2V_2}{C_1}=\frac{0.175%\times250\ mL}{5.25%}=8.3\ mL$.

Answer:

  1. C. $H_2O_2$
  2. A. Benzene ($C_6H_6$) and hexane ($C_6H_{14}$)
  3. C. $29.5%$ (v/v) ethanol
  4. C. $2.06\ M$ NaCl
  5. A. $8.3\ mL$ HCl solution